Negative Operational LL with DNO

Oselvar (A-1 H) – P&A

What happened:

Bottom 0.5 m of the toolstring is the Ultrasonic rotating IBCS-E sub. This sub has a larger OD (10.3″) . The top lip of the sub got caught on the rotary table when being lifted OOH with the tugger line. The tugger line continued to pull on the trapped toolstring until the string parted dropping the 0.5 m IBCS-E sub downhole.

What was planned:

POOH with SLB 13 3/8″ wireline IBC-CBL logging string (Isolation scanner). Recover string at surface and pull tools through the rotary table with tugger line and lay down to deck.

What was learned:

The tugger angle is not aligned over the well and the toolstring is pulled at an angle. Only one of the bowl segments had been removed, enough to give clearance for the IBC-E sub but more space would have been available should the second bowl segment be removed as well.

What actions are required:

Greater emphasis on the risk of getting tools caught at the rotary table when being recovered with the tugger line.

Avoid high pressure washing of tools when pulling through the rotary.

Remove both bowl segments prior to recovering any larger OD tools.

SLB to review the incident internally and distribute internally

SLB to add the incident and learnings to the SLB operational rig book for the Borgland Dolphin.

What Was Done

SLB have made a slide pack documenting the issue. SLB have started an internal investigation and will revert with recommendations. SLB engineer offshore has assured the DSV that the operational rig book will be updated so other engineers not familiar with the rig and this particular issue can be briefed about it.